The present disclosure relates to a power supply device, an electrical storage device, an electric vehicle, and an electric power system, in which a DC power supply is formed from different types of input power supplies.
In recent years, research and development for use of renewable energy have been active with the aim of a departure from dependence on fossil fuel. Solar power generation, wind power generation, fuel cells, biomass power generation, wave power generation, and the like have been developed as power generation utilizing renewable energy. When renewable energy is utilized, there is such a disadvantage that power generation amount varies due to natural conditions, and deficiency and excess of power generation amount with respect to power consumption occur. For example, a domestic power consumption amount may increase during a specific time of day, but this specific time may not necessarily agree with the time when an amount of power generation is large.
In order to address this disadvantage, it is conceivable to introduce a battery system into each household. In this system, an output of solar power generation or the like is temporarily stored in the battery system, and an output of the battery system is used to match with consumption. Specifically, the followings are performed in this system. For example, electric power may be flattened by feeding the output of the battery system to a system during a power-consumption peak time. Further, time shifting may be performed such that electric power is stored during a time when an electricity rate is low, and the electric power is discharged and consumed during a time when the electricity rate is high. Furthermore, surplus power of electric power generated by an electrical generator such as a solar battery may be stored in the battery system.
A system in which power generation, power transformation, power transmission, and power distribution used to supply electric power to a power incoming unit of a consumer are integrated is called a power system (or a system). A flow of electric power from the consumer to the electric power system is called a reverse flow, and feeding the electric power from the consumer to the electric power system is called regeneration. For example, electric power generated in a solar power generation system may be supplied to an electric power company. In this case, usually, a power conditioner is provided for the solar power generation system. The power conditioner converts an unstable DC output voltage of a solar battery into a stable DC voltage, and further converts a DC voltage into an AC voltage. The power conditioner performs control to keep tracking a maximum power point, by following variation in electric power generated by the solar battery (Maximum Power Point Tracking (MPPT) control).
In a case in which the output of the solar power generation system is used as a charging power supply for the battery system, only generation of DC power supply may be necessary and thus, it is not necessary to convert a DC voltage into an AC voltage. However, the MPPT control is necessary in tracking the maximum power point of the solar battery. Further, it is conceivable to use a commercial power supply as the charging power supply of the battery system. For a case in which DC power supply is generated from the commercial power supply, a power supply device having a PFC (Power Factor Correction) control IC may be suitable. This type of power supply device is capable of suppressing generation of a harmonic by improving a power factor.
For example, in Japanese Unexamined Patent Application Publication No. 2009-284646 (JP2009-284646A), a DC input and an AC input are both used, which one of AC and DC is inputted is determined, and an output of the determination is supplied to a control circuit of a boost converter. The control circuit controls boosting in the boost converter and PFC based on a result of the determination.